1. Field of the Invention
This invention relates to a system for monitoring turbomachine blade wear, and particularly to a system suitable for enabling an operator to remotely monitor blade wear. This invention further concerns selectively strobing a light to illuminate a particular blade or to automatically sequentially view blades in a predetermined pattern.
In recent years it has become desirable to employ turbomachines such as gas expanders in relatively harsh environments. In these harsh environments, the motivating fluid furnished to the turbomachine may be a "relatively dirty" gas containing much particulate matter. The particulate matter will cause erosion or other undesirable wear of the blades of the turbomachine.
As an example, gas expanders have been employed in association with fluid catalytic cracking processes (hereinafter F.C.C. process) employed by the petroleum industry. The gas expanders have been used to recover energy from waste heat gas streams which may contain entrained particulates such as catalyst particles. In particular, the expander receives the waste heat gas generated within a regenerator of the F.C.C. process whereby the waste heat gas functions as a motivating fluid for the expander. The expansion of the gas through the expander results in the generation of usable power. Similar expanders are used in coal gasification and analogous processes for recovering energy.
Generally, gas expanders of the foregoing type are located in positions which discourage constant monitoring by operating personnel. Although particulate matter separators are employed upstream of the expander not all particulate matter is removed. Further, the separator may become inoperative or the process conditions may change allowing large quantities of particulates to pass into the turbomachine. Impingement of particulates on the rotating blades will cause blade erosion. Erosion is generally a function of the quantity and size of particulate matter impinging on the blades. In multi-stage expanders, the blades mounted on the stage with the greatest operating load will be subject to the highest degree of erosion. Further, the trailing edge of the blade, as the thinnest portion thereof, is susceptible to the most significant erosion damage.
Even with operating separators, blades will constantly be undergoing erosion with the rate of erosion sometimes increasing substantially due to changes in the operating conditions of the F.C.C. process including such changes as process upsets. If blade wear due to erosion is not adequately monitored, one or more of the blades may fail causing severe, and in some circumstances, catastrophic events.
In addition to the foregoing, turbomachines such as steam turbines, may have blade failures due to carryover of moisture in the motivating fluid. In particular, moisture contained in the motivating fluid will impinge upon the blades of the turbomachine stages and effectively erode these blades.